Otolith δ18O and microstructure analyses provide further evidence of population structure in sardine Sardinops sagax around South Africa
Otolith δ18O and microstructure analyses provide further evidence of population structure in sardine Sardinops sagax around South Africa
复制标题
耳石 δ18O 和微观结构分析为南非沙丁鱼 Sardinops sagax 的种群结构提供了进一步的证据
DOI：
10.1093/icesjms/fsaa130
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发表时间：
2020
影响因子：
3.3
通讯作者：
Komatsu Kosei
中科院分区：
文献类型：
--
作者：
Sakamoto Tatsuya;van der Lingen Carl D;Shirai Kotaro;Ishimura Toyoho;Geja Yonela;Peterson James;Komatsu Kosei
沙丁鱼 Sardinops sagaxis 是一种具有重要生态和经济意义的鲽鱼，分布于整个南非海岸，包括沿海上升流和西部边界流系统。尽管沙丁鱼渔业的管理历史上假设存在单一的、泛滥的种群，但最近假设存在三个半离散的亚种群。我们进行了耳石 δ18O 和微观结构分析，分别研究了从南非海岸周围三个生物地理区域采集的沙丁鱼的育苗栖息地温度和早期生命生长率，以检验这一假设。分析表明，无论是夏季和冬季捕获的成鱼还是夏季捕获的幼鱼，西海岸的鱼类在比南海岸和东海岸温度低几度的水中生长速度明显减慢。这表明沙丁鱼在不同地区（特别是西海岸和其他海岸）之间的混合相对有限，并支持半离散亚种群的假设。然而，冬季捕获的幼鱼的结果中南北差异消失了，这表明地区之间早期生活条件的差异可能会随季节变化，和/或所有或大多数冬季捕获的幼鱼都来自西海岸。进一步阐明南非沙丁鱼亚群之间的相互作用及其机制对于该物种的可持续捕捞具有重要意义。
SardineSardinops sagaxis an ecologically and economically important Clupeid found off the entire South African coast that includes both coastal upwelling and western boundary current systems. Although the management of the sardine fisheries historically assumed a single, panmictic population, the existence of three, semi-discrete subpopulations has recently been hypothesized. We conducted otolithδ18O and microstructure analyses to investigate nursery habitat temperatures and early life growth rates, respectively, of sardine collected from three biogeographic regions around South Africa’s coast to test that hypothesis. Analyses indicated that for both summer- and winter-captured adults and summer-captured juveniles, fishes from the west coast grew significantly slower in water that was several degrees cooler than those from the south and east coasts. This suggests that mixing of sardines between regions, particularly the west and other coasts, is relatively limited and supports the hypothesis of semi-discrete subpopulations. However, the west-south differences disappeared in the results for winter-captured juveniles, suggesting that differences in early life conditions between regions may change seasonally, and/or that all or most winter-captured juveniles originated from the west coast. Further elucidating the interactions between South African sardine subpopulations and the mechanisms thereof is important for sustainable harvesting of this species.